1. Field of the Invention
The present invention relates generally to a projector, and more particularly to a fixed-focus projection lens.
2. Description of the Related Art
As the improvement of image technology, more and more people use a projector in presentation, video conference, meeting, and video watching. In order to improve the portability of the projector, the fixed-focus lens, which is mounted on the projector, is asked to be as small and light as possible. The fixed-focus lens is asked to have high optical performance also except for the weight and size to project images with high image resolution and contrast. Therefore, size and optical performance are the first two important facts for the fixed-focus lens of the projector.
In the conventional fixed-focus lens, there usually are three or more lens groups therein. Each lens group has several lenses, and the lenses are separated from each other. Consequently, the conventional fixed-focus lens is huge and heavy, and that is opposite to the modern design which requires the lens to be smaller and lighter. It takes a long time to manufacture the conventional fixed-focus lens because there are too much lenses, and of course, it has a high cost. Therefore, there still are some places that need to improve in the conventional fixed-focus lens for the projector.